Oral herpes is also known commonly as cold sores and fever blisters but is different entity from oral canker sores although canker sores may sometimes be associated with HSV infection. Canker sores occur solely inside the mouth. Oral herpes occurs inside and around the mouth. Most of the time HSV-1 causes mouth symptoms and in a minority of cases it may also be responsible for genital symptoms. The opposite is true for HSV-2 – it causes genital symptoms in the majority of cases while only a few cases of HSV-2 infection will result in mouth symptoms. HSV-1 infection may be seen in all ages, including children, but when genital herpes is seen in children, sexual abuse needs to be a consideration.
HSV infection causes several distinct medical disorders. Common infection of the skin or mucosa may affect the face and mouth (orofacial herpes), genitalia (genital herpes), or hands (herpetic whitlow). More serious disorders occur when the virus infects and damages the eye (herpes keratitis), or invades the central nervous system, damaging the brain (herpes encephalitis). People with immature or suppressed immune systems, such as newborns, transplant recipients, or people with AIDS, are prone to severe complications from HSV infections. HSV infection has also been associated with cognitive deficits of bipolar disorder,[13] and Alzheimer's disease, although this is often dependent on the genetics of the infected person.

With the first outbreak of herpes virus infection, an individual may also experience nonspecific flu-like symptoms like fever, swollen lymph nodes, headache, and muscle aches. It is also possible to have herpes virus infection without having any symptoms or signs, or having signs and symptoms that are so mild that the infection is mistaken for another condition.
Human herpes virus 2 (HHV2) is also called herpes simplex virus 2 (HSV2). It typically causes genital herpes, a sexually transmitted infection. However, it can also cause cold sores in the facial area. Like HHV1, the HHV2 infection is contagious and is spread by skin-to-skin contact. The main route of transmission is through sexual contact, as the virus does not survive very long outside the body.
Herpes virus type 5 is also known as cytomegalovirus. It is the major cause of mononucleosis. Mononucleosis causes symptoms similar to infectious mononucleosis. It is spread via blood transfusion, breast-feeding, organ transplants, and sexual contact. The virus causes diarrhea, or severe vision problems and even leads to AIDS. People with weakened immune systems are more susceptible to these diseases.

Following active infection, herpes viruses establish a latent infection in sensory and autonomic ganglia of the nervous system. The double-stranded DNA of the virus is incorporated into the cell physiology by infection of the nucleus of a nerve's cell body. HSV latency is static; no virus is produced; and is controlled by a number of viral genes, including latency-associated transcript.[70]
The “classic” symptoms that most people associate with genital herpes are sores, vesicles, or ulcers – all of which can also be called “lesions.” (The scientific literature on herpes uses the term “lesion” to describe any break or irregularity in the skin.) These classic lesions of genital herpes often resemble small pimples or blisters that eventually crust over and finally scab like a small cut. These lesions may take anywhere from two to four weeks to heal fully.

A doctor will base a presumptive diagnosis on information provided by the patient and on the physical examination. The characteristic appearance of the herpes sores leaves little doubt about the diagnosis, so the typical appearance of the sores is key to the diagnosis. This appearance helps distinguish oral herpes from oral thrush, shingles, gonorrhea, and syphilis. In addition, chapped or sunburned lips can resemble oral herpes, but the tissue stain (Tzanck smear, see below) shows no virus-induced cell changes. Further testing is usually not necessary but is sometimes done.
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